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<center><h1>CPM.java</h1></center><p><br>

Below is the syntax highlighted version of <a href = "CPM.java">CPM.java</a>.
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<pre><tt><span class="comment">/******************************************************************************</span>
<span class="comment"> *  Compilation:  javac CPM.java</span>
<span class="comment"> *  Execution:    java CPM &lt; input.txt</span>
<span class="comment"> *  Dependencies: EdgeWeightedDigraph.java AcyclicDigraphLP.java StdOut.java</span>
<span class="comment"> *  Data files:   </span><span class="url">http://algs4.cs.princeton.edu/44sp/jobsPC.txt</span>
<span class="comment"> *</span>
<span class="comment"> *  Critical path method.</span>
<span class="comment"> *</span>
<span class="comment"> *  % java CPM &lt; jobsPC.txt</span>
<span class="comment"> *   job   start  finish</span>
<span class="comment"> *  --------------------</span>
<span class="comment"> *     0     0.0    41.0</span>
<span class="comment"> *     1    41.0    92.0</span>
<span class="comment"> *     2   123.0   173.0</span>
<span class="comment"> *     3    91.0   127.0</span>
<span class="comment"> *     4    70.0   108.0</span>
<span class="comment"> *     5     0.0    45.0</span>
<span class="comment"> *     6    70.0    91.0</span>
<span class="comment"> *     7    41.0    73.0</span>
<span class="comment"> *     8    91.0   123.0</span>
<span class="comment"> *     9    41.0    70.0</span>
<span class="comment"> *  Finish time:   173.0</span>
<span class="comment"> *</span>
<span class="comment"> ******************************************************************************/</span>

<span class="preproc">package</span><span class="normal"> edu</span><span class="symbol">.</span><span class="normal">princeton</span><span class="symbol">.</span><span class="normal">cs</span><span class="symbol">.</span><span class="normal">algs4</span><span class="symbol">;</span>

<span class="comment">/**</span>
<span class="comment"> *  The </span><span class="keyword">&lt;tt&gt;</span><span class="comment">CPM</span><span class="keyword">&lt;/tt&gt;</span><span class="comment"> class provides a client that solves the</span>
<span class="comment"> *  parallel precedence-constrained job scheduling problem</span>
<span class="comment"> *  via the </span><span class="keyword">&lt;em&gt;</span><span class="comment">critical path method</span><span class="keyword">&lt;/em&gt;</span><span class="comment">. It reduces the problem</span>
<span class="comment"> *  to the longest-paths problem in edge-weighted DAGs.</span>
<span class="comment"> *  It builds an edge-weighted digraph (which must be a DAG)</span>
<span class="comment"> *  from the job-scheduling problem specification,</span>
<span class="comment"> *  finds the longest-paths tree, and computes the longest-paths</span>
<span class="comment"> *  lengths (which are precisely the start times for each job).</span>
<span class="comment"> *  </span><span class="keyword">&lt;p&gt;</span>
<span class="comment"> *  This implementation uses {</span><span class="type">@link</span><span class="comment"> AcyclicLP} to find a longest</span>
<span class="comment"> *  path in a DAG.</span>
<span class="comment"> *  The running time is proportional to </span><span class="keyword">&lt;em&gt;</span><span class="comment">V</span><span class="keyword">&lt;/em&gt;</span><span class="comment"> + </span><span class="keyword">&lt;em&gt;</span><span class="comment">E</span><span class="keyword">&lt;/em&gt;</span><span class="comment">,</span>
<span class="comment"> *  where </span><span class="keyword">&lt;em&gt;</span><span class="comment">V</span><span class="keyword">&lt;/em&gt;</span><span class="comment"> is the number of jobs and </span><span class="keyword">&lt;em&gt;</span><span class="comment">E</span><span class="keyword">&lt;/em&gt;</span><span class="comment"> is the</span>
<span class="comment"> *  number of precedence constraints.</span>
<span class="comment"> *  </span><span class="keyword">&lt;p&gt;</span>
<span class="comment"> *  For additional documentation,</span>
<span class="comment"> *  see </span><span class="keyword">&lt;a</span><span class="normal"> </span><span class="type">href</span><span class="symbol">=</span><span class="string">"http://algs4.cs.princeton.edu/44sp"</span><span class="keyword">&gt;</span><span class="comment">Section 4.4</span><span class="keyword">&lt;/a&gt;</span><span class="comment"> of</span>
<span class="comment"> *  </span><span class="keyword">&lt;i&gt;</span><span class="comment">Algorithms, 4th Edition</span><span class="keyword">&lt;/i&gt;</span><span class="comment"> by Robert Sedgewick and Kevin Wayne.</span>
<span class="comment"> *</span>
<span class="comment"> *  </span><span class="type">@author</span><span class="comment"> Robert Sedgewick</span>
<span class="comment"> *  </span><span class="type">@author</span><span class="comment"> Kevin Wayne</span>
<span class="comment"> */</span>
<span class="keyword">public</span><span class="normal"> </span><span class="keyword">class</span><span class="normal"> </span><span class="classname">CPM</span><span class="normal"> </span><span class="cbracket">{</span>

<span class="normal">    </span><span class="comment">// this class cannot be instantiated</span>
<span class="normal">    </span><span class="keyword">private</span><span class="normal"> </span><span class="function">CPM</span><span class="symbol">()</span><span class="normal"> </span><span class="cbracket">{</span><span class="normal"> </span><span class="cbracket">}</span>

<span class="normal">    </span><span class="comment">/**</span>
<span class="comment">     *  Reads the precedence constraints from standard input</span>
<span class="comment">     *  and prints a feasible schedule to standard output.</span>
<span class="comment">     */</span>
<span class="normal">    </span><span class="keyword">public</span><span class="normal"> </span><span class="keyword">static</span><span class="normal"> </span><span class="type">void</span><span class="normal"> </span><span class="function">main</span><span class="symbol">(</span><span class="normal">String</span><span class="symbol">[]</span><span class="normal"> args</span><span class="symbol">)</span><span class="normal"> </span><span class="cbracket">{</span>

<span class="normal">        </span><span class="comment">// number of jobs</span>
<span class="normal">        </span><span class="type">int</span><span class="normal"> N </span><span class="symbol">=</span><span class="normal"> StdIn</span><span class="symbol">.</span><span class="function">readInt</span><span class="symbol">();</span>

<span class="normal">        </span><span class="comment">// source and sink</span>
<span class="normal">        </span><span class="type">int</span><span class="normal"> source </span><span class="symbol">=</span><span class="normal"> </span><span class="number">2</span><span class="symbol">*</span><span class="normal">N</span><span class="symbol">;</span>
<span class="normal">        </span><span class="type">int</span><span class="normal"> sink   </span><span class="symbol">=</span><span class="normal"> </span><span class="number">2</span><span class="symbol">*</span><span class="normal">N </span><span class="symbol">+</span><span class="normal"> </span><span class="number">1</span><span class="symbol">;</span>

<span class="normal">        </span><span class="comment">// build network</span>
<span class="normal">        </span><span class="usertype">EdgeWeightedDigraph</span><span class="normal"> G </span><span class="symbol">=</span><span class="normal"> </span><span class="keyword">new</span><span class="normal"> </span><span class="function">EdgeWeightedDigraph</span><span class="symbol">(</span><span class="number">2</span><span class="symbol">*</span><span class="normal">N </span><span class="symbol">+</span><span class="normal"> </span><span class="number">2</span><span class="symbol">);</span>
<span class="normal">        </span><span class="keyword">for</span><span class="normal"> </span><span class="symbol">(</span><span class="type">int</span><span class="normal"> i </span><span class="symbol">=</span><span class="normal"> </span><span class="number">0</span><span class="symbol">;</span><span class="normal"> i </span><span class="symbol">&lt;</span><span class="normal"> N</span><span class="symbol">;</span><span class="normal"> i</span><span class="symbol">++)</span><span class="normal"> </span><span class="cbracket">{</span>
<span class="normal">            </span><span class="type">double</span><span class="normal"> duration </span><span class="symbol">=</span><span class="normal"> StdIn</span><span class="symbol">.</span><span class="function">readDouble</span><span class="symbol">();</span>
<span class="normal">            G</span><span class="symbol">.</span><span class="function">addEdge</span><span class="symbol">(</span><span class="keyword">new</span><span class="normal"> </span><span class="function">DirectedEdge</span><span class="symbol">(</span><span class="normal">source</span><span class="symbol">,</span><span class="normal"> i</span><span class="symbol">,</span><span class="normal"> </span><span class="number">0.0</span><span class="symbol">));</span>
<span class="normal">            G</span><span class="symbol">.</span><span class="function">addEdge</span><span class="symbol">(</span><span class="keyword">new</span><span class="normal"> </span><span class="function">DirectedEdge</span><span class="symbol">(</span><span class="normal">i</span><span class="symbol">+</span><span class="normal">N</span><span class="symbol">,</span><span class="normal"> sink</span><span class="symbol">,</span><span class="normal"> </span><span class="number">0.0</span><span class="symbol">));</span>
<span class="normal">            G</span><span class="symbol">.</span><span class="function">addEdge</span><span class="symbol">(</span><span class="keyword">new</span><span class="normal"> </span><span class="function">DirectedEdge</span><span class="symbol">(</span><span class="normal">i</span><span class="symbol">,</span><span class="normal"> i</span><span class="symbol">+</span><span class="normal">N</span><span class="symbol">,</span><span class="normal">    duration</span><span class="symbol">));</span>

<span class="normal">            </span><span class="comment">// precedence constraints</span>
<span class="normal">            </span><span class="type">int</span><span class="normal"> M </span><span class="symbol">=</span><span class="normal"> StdIn</span><span class="symbol">.</span><span class="function">readInt</span><span class="symbol">();</span>
<span class="normal">            </span><span class="keyword">for</span><span class="normal"> </span><span class="symbol">(</span><span class="type">int</span><span class="normal"> j </span><span class="symbol">=</span><span class="normal"> </span><span class="number">0</span><span class="symbol">;</span><span class="normal"> j </span><span class="symbol">&lt;</span><span class="normal"> M</span><span class="symbol">;</span><span class="normal"> j</span><span class="symbol">++)</span><span class="normal"> </span><span class="cbracket">{</span>
<span class="normal">                </span><span class="type">int</span><span class="normal"> precedent </span><span class="symbol">=</span><span class="normal"> StdIn</span><span class="symbol">.</span><span class="function">readInt</span><span class="symbol">();</span>
<span class="normal">                G</span><span class="symbol">.</span><span class="function">addEdge</span><span class="symbol">(</span><span class="keyword">new</span><span class="normal"> </span><span class="function">DirectedEdge</span><span class="symbol">(</span><span class="normal">N</span><span class="symbol">+</span><span class="normal">i</span><span class="symbol">,</span><span class="normal"> precedent</span><span class="symbol">,</span><span class="normal"> </span><span class="number">0.0</span><span class="symbol">));</span>
<span class="normal">            </span><span class="cbracket">}</span>
<span class="normal">        </span><span class="cbracket">}</span>

<span class="normal">        </span><span class="comment">// compute longest path</span>
<span class="normal">        </span><span class="usertype">AcyclicLP</span><span class="normal"> lp </span><span class="symbol">=</span><span class="normal"> </span><span class="keyword">new</span><span class="normal"> </span><span class="function">AcyclicLP</span><span class="symbol">(</span><span class="normal">G</span><span class="symbol">,</span><span class="normal"> source</span><span class="symbol">);</span>

<span class="normal">        </span><span class="comment">// print results</span>
<span class="normal">        StdOut</span><span class="symbol">.</span><span class="function">println</span><span class="symbol">(</span><span class="string">" job   start  finish"</span><span class="symbol">);</span>
<span class="normal">        StdOut</span><span class="symbol">.</span><span class="function">println</span><span class="symbol">(</span><span class="string">"--------------------"</span><span class="symbol">);</span>
<span class="normal">        </span><span class="keyword">for</span><span class="normal"> </span><span class="symbol">(</span><span class="type">int</span><span class="normal"> i </span><span class="symbol">=</span><span class="normal"> </span><span class="number">0</span><span class="symbol">;</span><span class="normal"> i </span><span class="symbol">&lt;</span><span class="normal"> N</span><span class="symbol">;</span><span class="normal"> i</span><span class="symbol">++)</span><span class="normal"> </span><span class="cbracket">{</span>
<span class="normal">            StdOut</span><span class="symbol">.</span><span class="function">printf</span><span class="symbol">(</span><span class="string">"%4d %7.1f %7.1f</span><span class="specialchar">\n</span><span class="string">"</span><span class="symbol">,</span><span class="normal"> i</span><span class="symbol">,</span><span class="normal"> lp</span><span class="symbol">.</span><span class="function">distTo</span><span class="symbol">(</span><span class="normal">i</span><span class="symbol">),</span><span class="normal"> lp</span><span class="symbol">.</span><span class="function">distTo</span><span class="symbol">(</span><span class="normal">i</span><span class="symbol">+</span><span class="normal">N</span><span class="symbol">));</span>
<span class="normal">        </span><span class="cbracket">}</span>
<span class="normal">        StdOut</span><span class="symbol">.</span><span class="function">printf</span><span class="symbol">(</span><span class="string">"Finish time: %7.1f</span><span class="specialchar">\n</span><span class="string">"</span><span class="symbol">,</span><span class="normal"> lp</span><span class="symbol">.</span><span class="function">distTo</span><span class="symbol">(</span><span class="normal">sink</span><span class="symbol">));</span>
<span class="normal">    </span><span class="cbracket">}</span>

<span class="cbracket">}</span>

<span class="comment">/******************************************************************************</span>
<span class="comment"> *  Copyright 2002-2015, Robert Sedgewick and Kevin Wayne.</span>
<span class="comment"> *</span>
<span class="comment"> *  This file is part of algs4.jar, which accompanies the textbook</span>
<span class="comment"> *</span>
<span class="comment"> *      Algorithms, 4th edition by Robert Sedgewick and Kevin Wayne,</span>
<span class="comment"> *      Addison-Wesley Professional, 2011, ISBN 0-321-57351-X.</span>
<span class="comment"> *      </span><span class="url">http://algs4.cs.princeton.edu</span>
<span class="comment"> *</span>
<span class="comment"> *</span>
<span class="comment"> *  algs4.jar is free software: you can redistribute it and/or modify</span>
<span class="comment"> *  it under the terms of the GNU General Public License as published by</span>
<span class="comment"> *  the Free Software Foundation, either version 3 of the License, or</span>
<span class="comment"> *  (at your option) any later version.</span>
<span class="comment"> *</span>
<span class="comment"> *  algs4.jar is distributed in the hope that it will be useful,</span>
<span class="comment"> *  but WITHOUT ANY WARRANTY; without even the implied warranty of</span>
<span class="comment"> *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the</span>
<span class="comment"> *  GNU General Public License for more details.</span>
<span class="comment"> *</span>
<span class="comment"> *  You should have received a copy of the GNU General Public License</span>
<span class="comment"> *  along with algs4.jar.  If not, see </span><span class="url">http://www.gnu.org/licenses.</span>
<span class="comment"> ******************************************************************************/</span>
</tt></pre>

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Last updated: Mon Mar 21 10:51:08 EDT 2016.
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